Vibratory compactors are commonly employed for compacting freshly-layed asphalt paving, soils, and similar materials. The compactor comprises a drum resiliently and rotatably mounted in a frame assembly wherein an eccentric mounting shaft arrangement is located and rotates relative to the drum. An exemplary vibratory compactor is illustrated in a commonly assigned copending application Ser. No. 308,748 which was filed Dec. 3, 1980. Such shaft arrangement selectively vibrates the drum to provide the desired compaction of the material being worked.
Apparatus for inducing vibration in such shaft arrangements has heretofore included the use of multiple weight members which are sequentially or concurrently radially displaced relative to the shaft arrangement so as to obtain the desired vibrating effect on the drum. Controlling the sequence of displacement of the multiple weights has been complex and, in addition manufacture and service of such weights has been relatively difficult. Multiple weights which were sequentially activated provided the means for vibrating the drum only for shaft rotation speeds above a predetermined minimum.
The present invention is directed toward providing a simple vibrating inducement apparatus as well as meeting the criteria of providing vibratory energy for rotation speeds greater than such predetermined minimum.